Merge #7068

7068: Add VSCode command to view the hir of a function body r=theotherphil a=theotherphil

Will fix https://github.com/rust-analyzer/rust-analyzer/issues/7061. Very rough initial version just to work out where I needed to wire everything up.

@matklad would you be happy merging a hir visualiser of some kind? If so, do you have any thoughts on what you'd like it show, and how?

I've spent very little time on this thus far, so I'm fine with throwing away the contents of this PR, but I want to avoid taking the time to make this more polished/interactive/useful only to discover that no-one else has any interest in this functionality.

![image](https://user-images.githubusercontent.com/1974256/103236081-bb58f700-493b-11eb-9d12-55ae1b870f8f.png)


Co-authored-by: Phil Ellison <[email protected]>

1 files changed, 25 insertions, 0 deletions

diff --git a/crates/ide/src/view_hir.rs b/crates/ide/src/view_hir.rs
new file mode 100644
index 000000000..cfcfb7cfb
--- /dev/null
+++ b/crates/ide/src/view_hir.rs
@@ -0,0 +1,25 @@
+use hir::{Function, Semantics};
+use ide_db::base_db::FilePosition;
+use ide_db::RootDatabase;
+use syntax::{algo::find_node_at_offset, ast, AstNode};
+
+// Feature: View Hir
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: View Hir**
+// |===
+pub(crate) fn view_hir(db: &RootDatabase, position: FilePosition) -> String {
+    body_hir(db, position).unwrap_or("Not inside a function body".to_string())
+}
+
+fn body_hir(db: &RootDatabase, position: FilePosition) -> Option<String> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(position.file_id);
+
+    let function = find_node_at_offset::<ast::Fn>(source_file.syntax(), position.offset)?;
+
+    let function: Function = sema.to_def(&function)?;
+    Some(function.debug_hir(db))
+}